Towable trailers are frequently coupled to a vehicle by a fifth-wheel trailer hitch. Such hitches have been used for decades. In the typical case, a fifth-wheel hitch is mounted on a pair of parallel rails, with the rails in turn mounted to the frame of the vehicle. The fifth-wheel hitch is typically located above, or forward of, the vehicle's rear-most axle. A trailer used with a fifth-wheel hitch includes a kingpin downwardly extending from the front portion of the trailer. The kingpin is coupled to the fifth-wheel hitch at a keyhole slot in the hitch by an articulating jaw. The jaw extends around the kingpin so as to prevent movement of the kingpin out of the keyhole slot. The articulating jaw is composed of mechanical parts which allow it to move between a locked and an unlocked position to allow the trailer to be coupled and uncoupled from the towing vehicle. As with any mechanical part, the articulating jaw is subject to mechanical failure. A typical towing vehicle has no safety mechanism which holds the trailer to the towing vehicle in the case of an articulating jaw failure. When a vehicle and trailer are traveling, failure of the articulating jaw generally results in the trailer coming loose from the vehicle, and can result in significant injury to person and property.